A high ignition temperature, thin-walled flame-retardant modified PP material and its preparation and application

Abstract

The present invention relates to a high ignition temperature, thin-wall flame-retardant modified PP material. The modified PP material comprises, by weight: 44.2-69.2 parts of PP resin; 15-25 parts of ammonium polyphosphate; 5-10 parts of PA6; 4-8 parts of a carbon forming agent; 4-8 parts of azodicarbonamide; and 1-5 parts of antimony-doped tin oxide. The modified material has good flame retardancy and ignition temperature GWIT at a relatively thin thickness (0.5 mm or less).

Description

Technical Field

[0001] The present invention belongs to the technical field of modified plastics, and particularly relates to a high ignition temperature, thin-wall flame-retardant modified PP material and its preparation and application. Background Art

[0002] Due to its advantages such as light weight, easy molding, corrosion resistance, non-conductivity, and low price, PP materials are widely used in traditional household appliance industries such as refrigerators, televisions, and washing machines. With the development of the Internet and the rise of the metaverse concept, smart wearable electronic products (such as smart watches, VR glasses, smart bracelets, smart clothing, etc.) are becoming more and more popular among consumers. Smart wearable devices usually have requirements for light weight to improve the wearing comfort of consumers. Components related to smart wearable devices usually adopt thin-wall technology, and the thickness of the parts is mostly about 0.5 mm; and the electronic components inside smart wearables are complex and connected to the power supply, so the materials used for smart wearables need to have good flame-retardant properties. PP has a low density and is very suitable for the light-weight requirements of smart wearables. However, the oxygen index of PP materials is relatively low and they are extremely easy to burn, so flame-retardant modification is required. However, traditional flame-retardant PP materials cannot meet the V-0 flame-retardant requirements when the thickness is 0.5 mm or less, and the ignition temperature GWIT is relatively low, making it easy to catch fire. Currently, the flame-retardant PP materials on the market cannot simultaneously meet the ignition temperature GWIT of 900 °C and the V-0 grade flame retardancy under the condition of a 0.5 mm thickness, and the flame-retardant PP materials used in the smart wearable industry generally have the disadvantages of a low ignition temperature GWIT and being unable to meet the thin-wall V-0 flame-retardant grade.

[0003] Chinese Patent CN112795147A discloses a high-GWIT flame-retardant PBT composition and its preparation method and application. This flame-retardant material has a relatively high GWIT temperature, but the parts are relatively thick. This flame-retardant PP cannot achieve V-0 flame retardancy at a thickness of 0.5 mm, and at the same time, it cannot meet the requirement of GWIT of 900 °C at an ultra-thin thickness of 0.5 mm. Chinese Patent CN102942739A discloses a high-CTI value, high-GWIT value environmentally friendly flame-retardant glass fiber-reinforced PP material and its preparation method. The GWIT of this flame-retardant PP material cannot reach above 900 °C. Chinese Patent CN112778734A discloses a high-CTI value flame-retardant PC. Although the GWIT of this material can reach above 900 °C, it cannot meet the requirement of V-0 at a thickness of 0.5 mm. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a high ignition temperature, thin-wall flame-retardant modified PP material and its preparation and application, so as to overcome the defect that PP materials in the prior art cannot have both a high ignition temperature and a good flame-retardant grade under thin-wall thickness.

[0005] The present invention provides a high ignition temperature, thin-wall flame-retardant modified PP material, wherein the modified PP material components include, by weight:

[0006]

[0007]

[0008] Preferably, the modified PP material components include, by weight:

[0009]

[0010] Preferably, the ammonium polyphosphate includes one or more of ammonium pyrophosphate, ammonium tripolyphosphate, and ammonium tetrapolyphosphate.

[0011] Preferably, the carbon-forming agent includes one or more of a pentaerythritol carbon-forming agent, a triazine carbon-forming agent, and a piperazine pyrophosphate carbon-forming agent.

[0012] Preferably, the PA6 accounts for 45-55% of the total weight of the PA6 and the carbon-forming agent.

[0013] Preferably, the weight fraction of antimony in the antimony-doped tin oxide is 6-14%, and more preferably 8-12%. The test method for the weight fraction of antimony refers to the standard YS / T 997.2-2014 "Chemical Analysis Method of Antimony-Doped Tin Dioxide", and is measured by cerium sulfate titration. When the weight fraction of antimony in antimony-doped tin oxide is less than 8%, the gas release of azodicarbonamide is uneven when heated, which will cause the local carbon layer to rupture and reduce the flame retardant performance. When the weight fraction of antimony exceeds 12%, the gas evolution rate of azodicarbonamide will be reduced, resulting in a decrease in the GWIT value.

[0014] Preferably, the modified PP material further comprises 0-1 part of other additives.

[0015] Preferably, the other auxiliary agents include antioxidants and / or lubricants.

[0016] Preferably, the antioxidant is present in an amount of 0.1-0.5 parts by weight.

[0017] Preferably, the antioxidant includes one or more of phenol antioxidants, phosphite antioxidants, and thioester antioxidants.

[0018] Preferably, the lubricant is present in an amount of 0.1-0.5 parts by weight.

[0019] Preferably, the lubricant includes one or more of erucamide, polyethylene wax, zinc stearate, and calcium stearate.

[0020] The present invention also provides a method for preparing a thin-wall flame-retardant modified PP material with a high ignition temperature, comprising:

[0021] Mix each component, feed the obtained premix into an extruder, melt, extrude, and pelletize to obtain a high ignition temperature and thin-wall flame-retardant modified PP material.

[0022] Preferably, the extruder is a twin-screw extruder.

[0023] Preferably, the melting temperature is 140 - 160 °C, the main engine rotation speed of the extruder is 190 - 200 revolutions per minute, the length-diameter ratio is 48:1 - 60:1, and the feeding rate is 500 - 800 kg / h.

[0024] The present invention also provides an application of a high ignition temperature and thin-wall flame-retardant modified PP material in smart wearable devices, such as in smart wearable products like VR glasses, smart watches, smart bracelets, etc.

[0025] The antimony-doped tin oxide involved in the present invention is doped with antimony pentoxide, where the tin oxide is tin dioxide.

[0026] The PA6 in the present invention has a relatively high amide group content, which is beneficial to promoting the rapid carbonization of the charring agent. The interaction between the two improves the carbonization efficiency, and a dense carbon layer can be formed even at a relatively thin thickness (0.5 mm and below), effectively isolating air and preventing combustion.

[0027] The decomposition temperature of azodicarbonamide in the present invention is 180 - 200 °C and it will not decompose during the preparation of the modified PP material.

[0028] Azodicarbonamide in the present invention will release a large amount of non-combustible gases such as nitrogen oxides and carbon dioxide when heated, taking away a large amount of heat, which can effectively increase the ignition temperature (GWIT value). Antimony-doped tin oxide can make the gas release of azodicarbonamide more uniform when heated, reducing the impact on the flame-retardant performance, and at the same time effectively increasing the GWIT value at an ultra-thin thickness. When the content of azodicarbonamide is less than 4 parts, the GWIT cannot reach 900 °C. When the content is higher than 8 parts, the excessive gas release will affect the flame-retardant effect, resulting in not meeting the flame-retardant V-0 level under the condition of a thin wall of 0.5 mm.

[0029] Beneficial effects

[0030] The added PA6 and charring agent in the present invention have a synergistic effect, improving the flame retardancy of the PP material at a relatively thin thickness (0.5 mm and below). The synergistic effect between azodicarbonamide and antimony-doped tin oxide increases the ignition temperature GWIT of the PP material at a relatively thin thickness (0.5 mm and below), while reducing the impact on the flame retardancy at a relatively thin thickness (0.5 mm and below). Specific Embodiments

[0031] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0032] Reagent source:

[0033] PP resin: K8003, Sinopec;

[0034] Ammonium polyphosphate: Ammonium tripolyphosphate, grade: Ammonium tripolyphosphate, manufacturer: Shandong Shouhua Chemical;

[0035] PA6: PA6 HY-2500A, manufacturer: Haiyang Chemical Fiber;

[0036] PA66: PA66 EPR27, manufacturer: Shenma;

[0037] Charring agent 1: Pentaerythritol charring agent: Tetrakis(hydroxymethyl)methane, grade: PM40, manufacturer: Aoluoji Chemical;

[0038] Charring agent 2: Triazine charring agent: Poly(2-aminoethylamino)-4,6-diamino-1,3,5-triazine, grade: FR-CFA, manufacturer: Yinyuan;

[0039] Charring agent 3: Piperazine phosphate charring agent: Piperazine pyrophosphate, grade: HF-T300, manufacturer: Conord New Materials;

[0040] Azodicarbonamide: SA5000D, Zhejiang Shuntai Technology;

[0041] Antimony-doped tin oxide 1: The weight fraction of antimony is 8%, grade: CP8C, manufacturer: Keeling&Walker;

[0042] Antimony-doped tin oxide 2: The weight fraction of antimony is 12%, grade: BITO, manufacturer: Keeling&Walker;

[0043] Antimony-doped tin oxide 3: The weight fraction of antimony is 6%, grade: CP5C, manufacturer: Keeling&Walker;

[0044] Antimony-doped tin oxide 4: The weight fraction of antimony is 14%, grade: CP150C, manufacturer: Keeling&Walker;

[0045] Tin dioxide: grade: Tin oxide, manufacturer: Jiangxi Renben Technology;

[0046] Other additives:

[0047] Antioxidant: Pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris(2,4-di-tert-butylphenyl) phosphite are compounded in a weight ratio of 1:1 and are commercially available;

[0048] Lubricant: Zinc stearate, commercially available;

[0049] Unless otherwise specified, a certain component (such as antioxidant, lubricant) in the parallel examples and comparative examples of the present invention is the same commercially available product.

[0050] The preparation method of the modified PP material includes: according to the ratios in Table 1, Table 2, and Table 3, fully mix each component in a high-speed mixer, and then feed it into a twin-screw extruder from the main feeding port, melt, extrude, and pelletize to obtain it. The processing conditions for melt extrusion are as follows: the temperature of the first zone is 140 - 150 °C, the temperature of the second zone is 140 - 150 °C, the temperature of the third zone is 140 - 150 °C, the temperature of the fourth zone is 150 - 160 °C, the temperature of the fifth zone is 150 - 160 °C, the temperature of the sixth zone is 150 - 160 °C, the temperature of the seventh zone is 150 - 160 °C, the temperature of the eighth zone is 150 - 160 °C, the temperature of the ninth zone is 150 - 160 °C, the main machine speed is 190 - 200 revolutions per minute, the length-diameter ratio is 48:1 - 60:1, and the feeding amount is 500 - 800 kg / h.

[0051] Performance test:

[0052] (1) Flame retardancy: The test standard is UL 94-2013, the thickness of the sample strip is 0.5 mm, record the flame retardancy grade, and record the extinguishing time t1 and t2 after two ignitions and the burning time. The shorter the t1 and t2 times, the better the flame retardancy.

[0053] (2) Ignition temperature GWIT: The test standard is IEC 60695-2-10:2013, and the thickness of the sample strip is 0.5 mm.

[0054] Table 1 Ratios of Examples 1 - 10 (parts by weight)

[0055]

[0056]

[0057]

[0058] Table 2 Ratios of Examples 11 - 15 (parts by weight)

[0059]

[0060] Table 3 Ratios of Comparative Examples (parts by weight)

[0061]

[0062]

[0063] As can be seen from Table 1-3, the flame retardant grade of the modified PP material at a thickness of 0.5 mm is V-0, t1 is 0.3 s - 7.9 s, t2 is 0.5 s - 6.2 s, and the ignition temperature GWIT is above 900 °C, such as 935 - 970 °C. In Comparative Example 1, PA6 is not added. In Comparative Example 2, the charring agent is not added. In Comparative Example 3, PA66 is used. The flame retardant grade and the ignition temperature GWIT of the modified materials in Comparative Examples 1-3 are significantly worse than those in Example 1 at a thickness of 0.5 mm. In Comparative Example 4, azodicarbonamide is not added. In Comparative Example 5, antimony-doped tin oxide is not added. The flame retardant grade and the ignition temperature GWIT of the modified materials in Comparative Examples 4-5 are significantly worse than those in Example 1 at a thickness of 0.5 mm. In Comparative Example 6, tin dioxide is used, and the flame retardant grade of its modified material is significantly worse than that in Example 1 at a thickness of 0.5 mm. In Comparative Examples 7 and 8, azodicarbonamide is not within the scope of the present invention. The ignition temperature GWIT of the modified material in Comparative Example 7 is significantly worse than that in Example 1, and the flame retardant grade of the modified material in Comparative Example 8 is significantly worse than that in Example 1 at a thickness of 0.5 mm. In Comparative Example 9, neither azodicarbonamide nor antimony-doped tin oxide is added, and the flame retardant grade and the ignition temperature GWIT of the modified material are significantly worse than those in Example 1 at a thickness of 0.5 mm. Thus, it can be seen that the added PA6 and charring agent in the present invention have a synergistic effect, improving the flame retardancy of the PP material at a thickness of 0.5 mm, while there is a synergistic effect between azodicarbonamide and antimony-doped tin oxide, increasing the ignition temperature GWIT of the PP material at a thickness of 0.5 mm and at the same time reducing the influence on the flame retardancy at a thickness of 0.5 mm.

Claims

1. A high ignition temperature, thin-walled flame-retardant modified PP material, Characterized in that, The components of the modified PP material include by weight parts: Among them, the charring agent includes one or more of pentaerythritol charring agent, triazine charring agent, and piperazine pyrophosphate charring agent; the weight fraction of antimony in the antimony-doped tin oxide is 6-14%.

2. The high ignition temperature, thin-walled flame-retardant modified PP material according to claim 1, Characterized in that, The components of the modified PP material include by weight parts:

3. The high ignition temperature, thin-walled flame-retardant modified PP material according to claim 1, Characterized in that, The ammonium polyphosphate includes one or more of ammonium pyrophosphate, ammonium tripolyphosphate, and ammonium tetrapolyphosphate.

4. The high ignition temperature, thin-walled flame-retardant modified PP material according to claim 1, Characterized in that, The PA6 accounts for 45-55% of the total weight of PA6 and the charring agent.

5. The high ignition temperature, thin-walled flame-retardant modified PP material according to claim 1, Characterized in that, The modified PP material further includes 0-1 part of other additives; the other additives include antioxidants and / or lubricants.

6. A preparation method of the high ignition temperature, thin-walled flame-retardant modified PP material according to any one of claims 1-5, Comprising: Mixing each component, feeding the obtained premix into an extruder, melting, extruding, and pelletizing to obtain a high ignition temperature, thin-walled flame-retardant modified PP material.

7. The preparation method according to claim 6, Characterized in that, The melting temperature is 140-160 °C.

8. An application of the high ignition temperature, thin-walled flame-retardant modified PP material according to any one of claims 1-5 in smart wearable devices.

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